Bradley, J.2008-02-272008-02-271986-09-01http://hdl.handle.net/1880/46287Modes of association are defined for the recursive associations that occur in bill of materials data bases and data bases for the family trees of corporations. It is shown that a series of useful modes may be explicitly defined. Modes of association may be schema defined to enable a relational data base system to capture more meaning about an association. When used with natural quantifiers and SQL/N, an upward-compatible extension of SQL, these modes permit construction of concise expressions for complex retrievals involving explosions and implosions of entities described in the data base. Full explosions/implosions may be expressed in SQL/N, which is not possible with SQL. A mode of association is a set of propositions, but may be defined and implemented as a relationship relation.EngComputer Scienceunknown1986-243-1710.11575/PRISM/30420